lt-
dont aim for 6 inches off the bottom. aim for about 1 foot over the fishes heads. (sometimes suspended) try a 1/2 oz to 3/4 oz egg wieght instead of pencil lead. this puts all of the weight right under the float in one spot instead of spread out and makes it easier to mend the line without pulling the float out of its intended course. use atleast a 9 foot rod to make mending easier as well. keep as much of the bow in your line out of the water and flip a bit of slack upstream of the float when the float gets even with you, this will stop the bow from dragging the float downstream and lifting your jig too high.

when the jig is above the fishes head and they take it you will know without any doubt.

if you fish the jig low and he takes it as it hits him in the head, you may only see the float hesitate for a second or vibrate a little. it is much more difficult to know if its a fish or just another rock. get the jig up a bit so that any hesitation or sideways movement on the float is an automatic hookset.

once you get good at reading the dink float you might want to try a round cork float. they are better at many types of water but you must know if you are fishing correctly because it wont read like a dink